At least 12 killed in suicide attack on Sunni mosque west of Baghdad where worshippers gathered for evening prayers.

At least 12 people were killed and 32 wounded when a suicide bomber wearing a vest packed with explosives attacked a mosque west of the capital Baghdad, officials have said.

The blast struck a Sunni mosque in Abu Ghraib, roughly halfway between Baghdad and the city of Fallujah, as worshippers gathered after midnight to pray, police and medics told the Reuters news agency early on Tuesday.

A separate report by the Associated Press news agency said the death toll was 14, citing police and hospital officials who spoke on condition of anonymity as they were not allowed to release information.

No group has yet claimed responsibility for the attack, which took place during the Muslim holy month of Ramadan.

The attack was the first in or around Baghdad since the Iraqi government declared victory on Sunday over the Islamic State of Iraq and the Levant (ISIL, also known as ISIS) in the city of Fallujah, further west.

Fallujah, in Anbar province, had been under the control of ISIL since January 2014.

The city, the first to fall to the armed group, was seen as a launching pad for recent ISIL bombings in and around the capital.

Its recapture by the government was part of a broader anti-ISIL offensive, which saw tens of thousands of civilians risk death to flee their homes, leaving Iraq to grapple with a humanitarian crisis as its forces prepare to launch an attack in Mosul, the last remaining major hub of ISIL in the country.